84 



ON DRAINING. 



Clay at ' Clay at 



22 inches 4 feet 6"iiiclies 



per cent. per cent. 



Silica 59-0 72-9 



Alumina 23-5 13-4 



Peroxide of iron 8-1 6*6 



Carbonate of lime 1 -0 0*8 



Water, with a little carbonaceous matter, ~i 



slight traces of magnesia, and sulphate [- 8'4 5'5 



of lime and loss -i 



Carbonate of magnesia 0*0 9"8 



100-0 100-0 



This is only one out of the numerous examples which I 

 could cite of the lower clay of a field being- more porous 

 than that nearer the surface. Beds of gravel, sand, or 

 mixed earth, also, often prevail under superficial clay, at 

 depths not too great to allow drainage to be made at dis- 

 tances considerably wider than if the drains were laid in the 

 clay, effecting- thereby the removal of the subterranean water, 

 permitting the descent of rain water, and causing a less out- 

 la}'' of money. 



The capillary force, or micculcncy of soils, varies greatly, 

 and is often very noticeable. It has occurred to me, in 

 digging test-holes previous to drainage, to find the water 

 standing in them not nearer the surface than 3 feet, yet 

 the surface soil has been so wet that water would drop from 

 it on squeezing with the hands. This exhibition would 

 determine me to bleed such soils to the depth of 5 feet at 

 least, and such drainage has been accompanied with com- 

 plete success. 



Although I am not a practical farmer, I think that I may 

 ver}^ confidently recommend to farmers the laying land 

 absolutely flat after efficient drainage. It is the practice of 

 many good agriculturists in the stiffest clays, who con- 

 sider that even a crease left on the surface is injurious to 

 drainage. 



Cavses of obstruction to Drarnarje. — Mr. Parkes describes 

 certain causes of obstruction to subterranean drains, with, 

 which, although fortunatel}^ few and limited in their extent, 

 every drainer should be acquainted, and ])repared to obviate 

 the inconvenience they might occasion. The first and most 

 extensive evil of this kind to which he refers, is the deposit 

 of a substance of an unctuous sticky natiu-e, in drains laid in 

 soils containing much ferruginous matter. Some portions 

 of Sir liobert Peel's estates at Drayton Manor were muck 



